Ad Blocking only works intermittently

[banhmi]

Expected Behaviour:

Ad Blocking should be working consistently

Actual Behaviour:

Ad blocking only works initially then after navigating around sites the ads will come back. Turning WifI On/Off again will trigger ad blocking again but ads will come back soon after.

When I view query logs I don't see client domains hitting pi-hole, only shows up in logs when it gets blocked or permit. It's like DNS is leaking to another source.

Update/Fix

DNS leaking due to secondary dns server (non pihile) being specified.

[technicalpyro]

When a device is "seeing ads| please open up command prompt and run ipconfig /all what we are looking for is if any other DNS servers are leaking through

[banhmi]

Ok! Guess its the secondary dns server being specified in dhcp thats causing the leak. Using it incase pihole is not working. Pretty sure it has previously all worked..anyway i'll leave secondary dns off for now.
Thanks!

[deHakkelaar]

This is explained here:

Why should Pi-hole be my only DNS server?

Reduced Ad Blocking Capability The main reason you should Pi-hole as your only DNS server is that you will see increased performance in the blocking of ads. If you have two DNS servers (Pi-hole and something else), your network clients may not always query Pi-hole for name resolution. If a query happens to be answered from a non-Pi-hole DNS server, your block lists will not apply (since that DNS server doesn't know about them). All Queries Need To Go Through Pi-hole First Since other DNS se…